The invention relates to a drive system comprising a shaft which is journalled to be rotatable in a frame and on which a plate is provided which cooperates with at least one sliding body. One flat side of the body cooperates with a running surface on the side of the plate which faces said body, this running surface being formed by a face which encloses an angle with the center line of the rotatable shaft. The sliding body is provided with a spherical face which cooperates with a corresponding face in a head of a drive rod, the arrangement being such that when the shaft rotates, the sliding body and the drive rod cooperating therewith perform a reciprocating movement.
Drive systems of the kind set forth are known and are referred to as swash-plate drive systems, as used in pumps, compressors and engines, in particular in hot-gas reciprocating engines, for imparting a given movement to the pistons, the reciprocating movement of the pistons being converted into a rotary movement of the plate and the shaft connected thereto. The forces of the pistons are then transferred to the plate by way of a sliding body. In order to limit the friction between and the wear of the sliding bodies and the plate, proper lubrication is required.
British patent specification No. 1,165,364 describes a drive system of the kind set forth in which the sliding bodies which are constructed as half spheres, bear on the flat plate by way of a hydrostatic lubrication film. Such a hydrostatic lubrication produces proper separation of the two surfaces, but the construction is complex and expensive.
In order to obtain a hydrodynamic lubrication film between sliding body and plate it has already been proposed to construct the side of the sliding body which cooperates with the plate to be slightly convex with a very large radius of curvature. This produces a wedge between sliding body and plate in which the lubricant is forced during operation, so that a lubrication film is obtained between sliding body and plate.
This rather simple step produces proper lubrication; however due to the wear occurring on the rather small sphere segment surface, particularly during starting, the convex shape will be lost after a comparatively short time, so that the body becomes flat and hydrodynamic lubrication no longer takes place.